76 ON VAKIETIES, KACES, SUB-SPECIES, AND SPECIES. 



groups without there being any possibility of affirming- that any 

 one of these groups contains unmodified individuals. 



In short, in the species to which the distinction Delta is appli- 

 cable, there are onh^ varieties, no individual types. 



We subjoin several examples of particular cases to which the 

 present distinction is applicable. 



Case 1. — Simple Varieties of a Type. 



Among the specimens of Primus Padiis (L.) some may be 

 found with a red fruit, but wliich are not capable of propagation 

 by seed with sutficient certainty to give rise to two varieties. 



If it had been demonstrated that the one proceeded from the 

 other, as it has been shown that tiie cultivated carrot has pro- 

 ceeded from the wild one, then the species Prunus Padus would 

 be comprised in the distinction Gamma; but as this is not the 

 opinion of the generality of botanists, we think it better to apply 

 to this species the distinction Delta 1. 



The species Helix jiulchella is, according to M. Agassiz, ano- 

 ther exaniple of this ; there are two varieties of the latter species — 



a. — Even. 



^'.— Kibbed. 



Case 2. — Varieties of Type, and Races derived therefrom. 



What we have already stated is applicable to the Wild Cherry 

 {Ceras?(s aviu?n). In the impossibility wliich exists in affirm- 

 ing that the type of the species has black, red, or even white 

 fruit, we are compelled to consider the individuals which pre- 

 sent these differences as two or three varieties of one type, and 

 consequently to apply to this plant the distinction Delta. But 

 the Wild Cherry is not like the Prunus Padus, for botanists 

 and gardeners all agree that from the former three distinct races, 

 viz. the Guigne, Bigarreau, and Heaunie, have been obtained 

 by cultivation ; these races, at least the two first, may be pro- 

 pagated with considerable constancy by seed, and what is very 

 remarkable, each of them includes varieties, the fruit of which, 

 by their black, red, or white colour, corresponds to the three 

 typical varieties. 



Case 3. — Paces derived from, an unknown or imperfectly 

 known type. 



When a great many varieties, or when many races capable of 

 propagation from seed, have been obtained from a plant cultivated 

 for a long time in countries to which it is not indigenous, it may 

 be very difficult, even in these countries, to point out the type 

 from which these varieties have proceeded, and to ascertain the 



